GB751153A - Improvements in or relating to apparatus for guiding electromagnetic wave energy - Google Patents

Abstract

751,153. Transmission lines and waveguides. WESTERN ELECTRIC CO., Inc. April 26, 1954 [April 29, 1953], No. 11969/54. Class 40 (8). Apparatus for guiding an electromagnetic wave comprises a magnetic transmission line or waveguide consisting of one or more magnetic conductors of highly permeable electrically non-conductive material such as a ferrite which guide the wave energy by their influence upon the magnetic field component. The transmission line of Fig. 1 comprises two parallel elements 12, 13 of ferrite shunted at their ends by magnetic elements 14, 15 around which are wound input and output coils. The inner and outer conductors 21, 22 of the magnetic coaxial line of Fig. 2 are made of ferrite, the couplings to and from the line consisting of windings 23, 26 around the inner conductor. Terminating end plates 25 of ferrite are so placed that energy reflected from the plates combines in phase with that coupled to or from the windings 23, 26. Wave energy is transmitted in the magnetic coaxial line in a mode resembling that of the H 01 circular waveguide. The losses in a magnetic coaxial line may be reduced by loading it with a material of high dielectric constant such as barium titanate. The loading may be continuous or in the form of spaced septa. Another method of loading consists in providing transverse cuts or discontinuities in either the inner or outer members of the line. To achieve a high electrical impedance of the bounding members in the peripheral direction the inner and outer members 71, 72, Fig. 7, may consist of alternate strips of high-permeability and high-permittivity material. The interspace between the inner and outer members may be loaded with material 73 of high permittivity. Transverse cuts may be provided in the outer or inner member. The inner member may be omitted and the magnetic field of the wave guided by a single boundary. The guide may be in the form of rod of ferrite the waves being propagated in the space around the rod. Fig. 9 shows a hybrid coaxial line in which wave energy in the normal mode is guided by copper strips 93 whilst energy of a different mode is guided by the inner and outer ferrite members 91, 92 in the manner described with respect to Fig. 2. An alternative form of hybrid guide comprises inner and outer cylindrical copper members with ferrite strips on the inner surface of the outer member and the outer surface of the inner member (Fig. 11 not shown). Longitudinal slots may be provided in the inner and outer members in either modification. Loading in the form of spaced cylindrical members of high permittivity may be provided in the interspace.